Process for treating hydrocarbons



Sept. 6, 1932.

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Patented Sept. 6, 1932 UNITED STATES PATENT OFFICE WALTER 'M. CROSS, OFKANSAS CITY, MISSOURI, ASSIGNOR, BY MESNE ASSIGNMENTS,

T0 GASOLINE PRODUCTS COMPANY, INC.,'OF WILMINGTON, DELAWARE, A CORIfO-RATION OF DELAWARE rnoonss FOR TREATING mnocannons Application filedOctober 8, 1923. Serial No. 667,380.

granted Oct. 31, 1916, which process did not permit a fresh sup 1y ofhydrocarbon oil to be continuously fed to the apparatus but was operatedintermittently. An apparatus continuously operated as herein explainedhas the advantage of producing more uniform and better results in theway of an increased quantity and better quality product.

Among the advantages of the invention are an increased economy inoperation, not only in fuel consumption, but also in theamount of oilthat can be treated over a given period of time. A further advantage isthat inasmuch as in the continuous process, the temperature can bemaintained substantially constant for relatively long periods of timeinstead of alternate heating and cooling, the

life of the apparatus will be correspondingly prolonged as there will bemuch less strain, due to rapid expansion and contraction.

Further, the process permits of the continuous treatment of hydrocarbonswhereby oil is treated to heat and pressure conditions regulated toeffect a conversion or cracking which takes place without materialvaporization and substantially while the oil is maintained in the liquidphase. The process further provides for the intermittent or continuouswithdrawal of this converted oil from the zone of reaction while thesame is in a heated condition, and provides for the distillation of thisheated product in a sepafractionation ofthe oil takes place underreduced pressure conditions relati ve\the conditions maintained in thecracking stage.

The process is such that this distillation may take place primarily dueto the reduced pressure conditions without'the addition of heat, or, asis the case with certain oils, heat may be added to the distillationstage to produce the desired amount of overhead products.

An additional feature of the process is the returning of the distillateproduced by the condensation of the distilled-oil to the cracking stageand there combining it with the charging stock to be introduced to thecracking stage for retreatment.

' In the drawings:

Fig. 1 is a general viewof the apparatus with parts broken away toreduce the size of the drawing.

Fig. 2 is a vertical sectional view of the tube arrangement on anenlarged scale.

Fig. 3 is a view, partly diagrammatic and partly in section, of myimproved apparatus.

Fig. 4 is a transverse sectional view taken on lines 44 of Fig. 3 but onan enlarged scale.

Referring to Figs. 1 and 2, 1 designates a. furnace having the usualfire box 2, abovewhich is located a series of tubes 3, opening at theiropposite ends into hollow plates 4 and 5. A plurality of baflle plates 6and 7 are employed in the furnaces for forcing the hot gases alongsubstantially the entire length of the tubes 3 before passing to thestack 8. Opening into the lower portion is an inlet 9 connected to asource of supply in the manner hereinafter described and at the'upperend of the end plate 5 is an outlet 10 connected by a conduit 11 withconverter tank 12. Leading from this converter tank is a pair ofdischarge pipes 13 and 14, the latter of which connects with a reheater15, and the former is connected with the inlet pipe 9. Referring to Fig.3, 1, 1a,1b, 1c, 1d, 10 represent a plurality of furnaces. '18, 18a,18?), etc. representing the circulating pumps 19, 19a, 196, etc.represent the motors to the same. 13, 13a, 136, etc. and 11, 11a, 116etc.

represent the circulation pipes. In the drive the same, 37 the intake tosaid pump, and 35 is a feed pipe extending from the pump 33 and emptyinginto the chamber 12.

In the employment of this apparatus, it is contemplated that thesubstance treated will circulate from the convertor tank 12 freelythrough the furnace tubes 3 (Fig. 2) of the heating furnaces 1, 1a, 16,etc. and back into the convertor tank 12. In order to cause thiscirculation, pumps 18, 18a, 18?), etc. are employed for forcing the oilthrough the inlets 9 of the heating tubes 3. As shown, these pumps aredriven by motors 19, 19a, 196, etc, both pumps and motors being mountedon the common bases 20, 20a, 206, etc. The passage through the variouspipes is controlled by suitable valves, a cutoff valve 22 is in positionon the pipe l l for controlling the passage of treated oil from theconverter tank 12 to the still 15. Also the pipe 31 is provided with acutofi valve 32 for controlling the flow of vapor from the convertor 12direct to the condenser 10. A pipe 28, leading from the still 15,communicates with a precooler 29 which comprises a coil subjected toatmospheric conditions or otherwise cooled. A check valve is interposedin the line 28. The discharge end of the precooler is connected by aline 38, controlled by a check valve 39, to a condenser coil 10 mountedin the water-cooled condenser box 41. natiorr or discharge end of thiscoil is controlled by a valve 42, from which may be drawn 03, eithercontinuously or intermittently, the final distillate. A line 43, tappedinto the lower part of the precooler, connects with a receiving tank 4%which in turn has a liquid draw-0d line 15 regulated by valve 46. Thisliquid drawofi line communicates with the suction side of the pump 33 bymeans of which the condensate separated out in the precooler may bereturned, combined with the charging stock in the line 37 to beintroduced therewith into the convertor tank 12.

In starting the process, the intake 37 of the pump 33 is connected witha suitable supply of oil to be'treated. Then the pump 33 is started anddriven by the motor 36, pumping the oil into the convertor 12 throughthe intake 35. As soon as sufficient oil is pumped into the apparatus,one-third full more or less, the circulating pumps 18, 18a, 18?), etc.are all started and/ heat is applied in the furnaces 1, 1a,'lb, etc; Nowthe pump 33 is stopped, and the heat is applied in the furnaces 1, 1a,1?), etc. until the pressure in the apparatus reaches the point that itincreases out of proportion to the temperature, that is, when such atemperature is reached that pressure begins to rise without any furtherincrease in temperature, the pressure in this case being that pressuredue to the vapors from the hydrocarbons subjected to the treatment beinggenerated by the heat. New this reacting temperature is maintained forThe termirsvaeee a period of thirty minutes, more or less, according tothe character of the oil used. In

any event, the temperature is maintained in the apparatus until asubstantial amount of conversion products or gasoline-like products isobtained or formed in the oil itself. After this reacting time has beenallowed, the valve 32 is opened sufliciently to permit suchincondensible gases to escape to prevent an excessive rise in pressureand the pump 33 again started so that the discharge of oil through thepipe 14 together with any discharge of vapor is replaced by the oil thatis pumped through the intake simultaneously. If the pressure becomesexcessive, the valve 32 is opened and some of the vapors are allowed topass out through the pipe 31 into the condenser 40 and then discharged.If satisfactory condensation and separation of condensible vapors fromnoncondensible vapors is not accomplished, in the condenser 29 when itis operated at atmospheric pressure, the valve 42 on the outlet of thecondenser is partially closed so that suiiicient pressure is built up inthe condenser 40 so as to insure satisfactory separation of thecondensible from incondensible vapors in the condenser &0. Whensufiicient oil has been discharged through the pipe 1 1 into the still15 so as to partially fill it, fire is started and a distillate ofgasoline or gasoline-like products is driven over through the vapor line28 into the condenser 40. Simultaneously vapor may also be deliveredinto the condenser 40 through the pipe 31 and valve 32. The oil, afterhaving been subjected to conditions of heat and pressure in the heatingunits and convertor tank 12, results in a synthetic crude produced whilethe oil is maintained substantially in the liquid phase. and withoutmaterial vaporization. This synthetic crude while in the conversionstate or highly heated condition is transferred either intermittently orcontinuously to the still 15 and is there distilled under reducedpressure conditions or under substantially atmospheric pressure, Ifsatisfactory condensation and separation of the condensible vapors fromnoncondensible vapors is not accomplished in the condenser 40 when it isoperated at atmospheric pressure, the valve d2 on the outlet of thecondenser is partially closed so that sufficient pressure is built up inthe condenser 40 so as to insure satisfactory separation of condensiblefrom noncondensible vapors in the condenser 40. The heated oil directedto the still 15 is normally at such temperature that a distillation isetllected without addition of heat but merely due to the reduction ofpressure. Oils of a certain character, however, require additional heatto produce satisfactory overhead distillation, and for this purpose heatmay, if desired, be added to the oil in the still 15. Such oils askerosene and hydrocarbons up I distillation stage to'promote theevolution of the more volatile fractions. Simultaneously vapor may alsobe delivered into the condenser 40 through the pipe 31 and valve 32. Thelength of the convertor chamber 12 and E the number of heatingfurnaces1, 1a, 1?), etc.

will be determined entirely by the amount of oil that is to be treatedin any one 24-hour period. The oil in this process, after it is started,is pumped in at such a rate that it will remain in the apparatus and besub.

jected to the reacting temperatures thirty minutes more or lessaccording to the time required for producing gasoline or gasolinelikebodies. A pressure of from 100 to 800 pounds may be maintained, thisvarying with conditions. The oil introduced to the chainber 12 by meansof the pump 33 is circulated through the heating coils and back to thebulk supply, and in its travel through the cracking zone, is brought toa conversion temperature, being subjected during this heat treatment topressure conditions sufficient to cause the conversion to take placewithout substantial vaporization.

It is self-evident that the longer the converter chamber 12 and the morenumerous the furnaces 1, 1a, 1?), etc. the more rapidly oil can bepumped into the apparatus and still allow the necessary reactive timefor the production of the gasoline-like product. In order that the oilmay not circulate by convection backward, baflie plates 34a, 34b, 34c,34d, 340, etc. may be placed in the vapor chamber 12 at right angles toits longitudi nal dimensions. A cross section of the convertor chamber12 with baffle plates 34a, etc. is shown in Fig. 4. The heighth of thisbaffle plate is one-fourth the diameter of the vapor chamber 12, more orless according to the amount of oil that is being carried in theapparatus during the operation.

The operation of this process provides means for continuous operationand recovcry of gasoline and gasoline-like products during the operationof the process. It is also well known that if a hydrocarbon oil is beingsubjected to a cracking process or a conversion process, whereby lighterhydrocarbons are formed that there are also formed methane and othergases, which cannot be condensed into a liquid at atmospherictemperature. The amount of methane and non-condensible gas then isproportioned to the amount of like product that is condensible into aliquid at atmospheric temperature.

drawn.

In the operation of this process, such pressure is produced thatgasoline or gasolinelike bodies may exist in the liquid phase, althoughthe temperature may be somewhat high, that is, from 350 to 450 C. ormore. 7 Now if the oil containing this gasoline is withdrawn through theline 14 and a less proportion of noncondensible vapor is withdrawnthrough the line 31 then the tendency is for an excessive amount ofgasoline to be formed from the hydrocarbons inasmuch as the methane andother noncondensible vapors are not withdrawn to the same extent as thegasoline and therefore, do not have to be formed to establish thechemical equilibrium in as great amount as would be the case if thenon-condensible gas and the oil were entirely withdrawn at the sametime. Laboratory apparatus operated in this way, showed conclusivelythat if, during the ,operation of the process, non-condensible gas waswithdrawn, a larger amount of gas formed than is the case were it notwith- Also it was demonstrated that if gasoline were removed from theapparatus while the process was in operation, that a somewhat largeryield was obtained than was the case when the noncondensible gas wasremoved at the same time. It was necessary, however, to remove some ofthe noncondensible gas as the pressure rose excessively high if it wasnot done, provided the gasoline was withdrawn and new oil pumped induring the operation of the apparatus. Briefly, the process is such thatthe oil is 100 preferably circulated through coils 3 in the separateheating units and into the reaction chamber 12, and thence back to thecoils and through the pipe 13 until the temperature of the oil has beensufficiently raised. During 105 this circulation, and with the rise intemperature, gaseous vapors are evolved which exerted pressure on theoil sufficient to prevent substantial vaporization of the bulk of theoil undergoing circulation. The heat and 110 temperature are socontrolled that the cracking takes place while the oil is maintainedsubstantially in the liquid phase. When the system has becomesufficiently heated, oil may be continuously introduced to the sys- 115tem and pass slowly therethrough, during which period it will besubjected to the temperature and pressure conditions maintained thereinand undergo cracking. Simultaneously with this continuous introductionof 120 oil, the converted product may be withdrawn either continuouslyor intermittently through the transfer line 14 and distilledunderreduced pressure conditions with the contained heator with the additionof heat i products from the cracking stage to prevent I for aretreatment in the cracking stage. The

uncondensed portions of the vapors passing from the precooler aresubjected to a final condensing action in the condenser coil 40. Theselatter vapors comprising principally those'fractions which producegasoline-like bodies. As'explained, the reflux or condensate separatedout of the precooler, is recycled for retreatinent with the charging andpressure, continuously withdrawing oil from the said body separate fromcondensible ,and incondensible gases generated from said body andpassing the 'oil without cooling to a still into which the oil isreleased at atmospheric pressure without intermingling with saidcondensible and incondensible gases and without intermingling with ahigher temperature inert heating medium whereby the lighter fractionswill distill off, condensing such lighter fractions, and taking offcondensible and incondensible gases from the cracking stage to preventan excess rise in pressure.

2. An improvement in the art of oil conversion for the purpose ofproducing lighter from heavier hydrocarbon products by pyrogenesis,which consists in maintaining a considerable body of oil under crackingconditions of temperature and pressure, continuously withdrawing oilfrom said body separate from condensible and incondensible gasesgenerated from said body of oil and passing the oil without cooling to astill into which it is released at a reduced pressure withoutintermingling with said condensible and incondensible gases and withoutintermingling with a higher temperature inert heating medium whereby thelighter fractions will distill off, condensing such lighter fractionsand taking off condensible and incondensible excess rise in pressure. v

3. An improvement in the art of oil conversion for. the purpose ofproducing lighter from heavier hydrocarbon oil which comprises passingsaid heavier hydrocarbon oil in a relatively small stream through aheating zone, wherein it is heated to cracking temperature, conductingthe oil from said stream after heating to an enlarged body of oillocated outside of said heating zone, maintaining cracking conditions oftemperature and pressure on said body, continuously withdrawing oil fromsaid body and passing the oil without'cooling and without interminglingwith a higher temperature inert heating medium to a zone of reducedpressure whereby the lighter fractions are distilled off, condensingsuch lighter fractions and taking off condensible and incondensibleproducts from the cracking stage to prevent excessive rise in pressure.

4:. An improvement in the art of oil conversion for the purpose ofproducing lighter from heavier hydrocarbon products by pyrogenesis,which comprises maintaining a considerable body of oil under crackingconditions of temperature and pressure, continuouslywithdrawing oil fromsaid body, pass ing the oil to a still without intermingling with ahigher temperature inert heating medium into which it is released at areduced pressure whereby the lighter fractions are vaporized, removingthe vaporized lighter fractions from said still, separating the removedvaporized fractions into a lighter portion and a heavier portion takingoff condensible and incondensible products from the cracking stage toprevent excess rise in pressure and contacting said products with onlysaid light portion of said vaporized fractions.

5. An improvement in the art of oil conversion for the purpose ofproducing lighter from the heavier hydrocarbon products which comprisesmaintaining a considerable body of oil under such cracking conditions oftemperature and pressure as to prevent substantial distillation of thelighter oil fractions, continuously withdrawing oil from the body andpassing the oil withdrawn to a stage into which it is released atreduced pressure whereby the lighter fractions will distill off,condensing such lighter fractions and separately taking offincondensible gases from the cracking stage to prevent excess rise inpressure.

6. A process in accordance with claim 5 wherein the incondensible gasestaken off from the cracking stage are combined with said lighterfractions prior to the final condensation of said fractions.

WALTER M. CROSS.

